Optimizing radiofrequency ablation parameters for perianal fistula treatment: A porcine model study

초록

BACKGROUND The effective treatment of perianal fistulas while ensuring sphincter preservation remains challenging. Radiofrequency ablation (RFA) is a promising approach; however, its clinical translation is limited because energy settings have been extrapolated from non-fistulous tissues, and most probes deliver only focal heating. We designed a 50-mm segmental RFA catheter to achieve maximal granulation tissue ablation while maintaining uniformity along the tract. AIM To identify the optimal temperature-time parameters for uniform, effective endoluminal RFA of perianal fistulas. METHODS Ex vivo screening in fresh pork loin selected four candidate energy settings defined by temperature and duration: 120 degrees C/20 seconds, 120 degrees C/24 seconds, 100 degrees C/20 seconds, 100 degrees C/24 seconds. These were applied endoluminally to the perianal fistula tracts created in four pigs. After RFA, each tract was divided into the inner, middle, and outer thirds for histological analysis. The primary endpoint was the ablation-to-granulation tissue area ratio, and burn depth was summarized as the equivalent radius (re). RESULTS The 120 degrees C/24 seconds setting achieved the highest ablation-to-granulation ratio (70.9 +/- 7.5%), exceeding 120 degrees C/20 seconds (51.9 +/- 8.3%), 100 degrees C/20 seconds (46.9 +/- 4.0%), 100 degrees C/24 seconds (43.7 +/- 6.1%). It also produced the greatest burn depth (re 0.46 +/- 0.05 mm vs 0.30 +/- 0.04 mm, 0.24 +/- 0.03 mm, and 0.19 +/- 0.03 mm; all pairwise P < 0.001). The depth was consistent across segments. CONCLUSION In a porcine fistula model, segmental RFA at 120 degrees C for 24 seconds produced the deepest, most homogeneous ablation, supporting its use as a reference setting for further studies.

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